Analysis of Axial Compression Mechanical Performance of Circular Hollow Sandwich Stainless Steel Pipe Concrete Short Columns

Literature Overview

This paper by Peng Guihan, Song Chunsheng, Luo Huiling, and Wang Jie, published in the Journal of Nanchang University (Science and Technology) in 2020, presents a systematic investigation into the axial compression mechanical behavior of circular hollow sandwich stainless steel pipe concrete (HSS-CFST) short columns. The research was funded by the Fujian Provincial Natural Science Foundation (2018J01769) and the Fujian Provincial Department of Education Middle-aged and Young Teacher Educational Research Project (JAT170791). The authors established a benchmark finite element solid model based on experimental data and conducted parametric analyses on key parameters including the hollow ratio, concrete strength, and inner and outer steel tube strengths. They also proposed a structural load-bearing capacity correction algorithm and examined the applicability of current domestic and international codes for calculating the load-bearing capacity of such structures.

Core Technical Findings

The study reveals several important relationships governing the structural behavior of HSS-CFST columns. Within the investigated parameter range, both concrete strength and outer steel tube strength exhibit a linear positive proportional relationship with the structural load-bearing capacity. This linear proportionality is significant from a design perspective because it simplifies the scaling of material properties to structural performance.

A particularly notable finding concerns the effect of the hollow ratio on load-bearing capacity. For high-strength inner steel tubes, the HSS-CFST structure consistently outperforms the solid counterpart in terms of load-bearing capacity across different hollow ratios. The load-bearing capacity increases with the hollow ratio initially and then decreases, reaching its maximum at a hollow ratio of 0.46. This non-monotonic behavior suggests an optimal hollow ratio that balances the trade-off between material reduction and structural integrity.

The proposed structural load-bearing capacity correction algorithm demonstrates good agreement between calculated and experimental values, indicating that the methodology is reliable for practical engineering applications. Furthermore, the study concludes that current domestic and international code calculation methods are all conservative when applied to this type of structure, which implies potential for more efficient material utilization.

Key Parameters and Design Implications

The optimal hollow ratio of 0.46 represents a critical design parameter. At this ratio, the structure achieves maximum load-bearing capacity, suggesting that designers can reduce material usage by approximately 46 percent of the cross-sectional area while maintaining or even improving structural performance, provided that high-strength inner steel tubes are employed.

Code Applicability Assessment

The finding that existing codes are conservative for HSS-CFST structures carries significant engineering implications. Conservative design methods, while safe, often lead to material overuse and increased construction costs. The proposed correction algorithm offers a pathway toward more rational design that leverages the actual structural capacity of these hybrid systems. Engineers should note that the conservatism observed may stem from the codes not fully accounting for the confinement interaction between the hollow sandwich configuration and the concrete core, or from the unique stress distribution patterns that differ from conventional solid CFST columns.

Study Insights and Engineering Practice Integration

From a materials engineering perspective, the use of stainless steel for both inner and outer tubes introduces additional considerations regarding corrosion resistance and long-term durability, which are critical for infrastructure applications in harsh environments. The hollow sandwich configuration not only optimizes material efficiency but also provides inherent protection to the inner concrete core from environmental degradation. The linear relationship between material strength and structural capacity simplifies the selection of appropriate material grades for specific load requirements. For practical implementation, engineers should pay close attention to the welding quality between the inner and outer tubes and the concrete filling process, as these factors can significantly influence the actual performance relative to the theoretical predictions. The correction algorithm proposed in this study should be validated through additional experimental work before widespread adoption in design practice, particularly for structures operating under complex loading conditions beyond simple axial compression.